not sure it would be good w/ actual "fire" under it- but have ya ever thought of bowling up a pizza pan w/ holes- i've used the cheapies in old smokeys for a coal pan- just never thought of using 1 of those non stick pans- i hear bad things about gases they let off over 500 degrees(w/ live fire on it it's over 500)- just a thought
I was going to question how many coals you had in the pan and how you lite them? I had one friend light them like you would on a regular grill, lighter fluid all over and whooosh!! I have a GOSM vertical and the charcoal pan is on the bottom, near the vents. There are six slide in racks. The first one from the bottom is where my water pan goes. When I am looking for more heat, I switch to playbox sand. You may also want to go with luke warm water over cold. Living in Florida we have tons of humidity and water in the pan is not really necessary. We just do alittle spritzing on the way to keep things moist.
My little thoughts on your problem, and i did not see this stated as i flew thru the responses, but the big pans should be on the bottom and smaller on top this way heat has more space between the smaller water pan and the sides to flow upward. Hope this helps a little